Replacing protein in corn-soybean turkey diets with methionine and lysine.

The extent to which dietary protein can be minimized by using Met and Lys supplements for market turkeys has been investigated in three experiments involving 2,750 birds. Large White (Nicholas) male turkey poults were fed corn-soybean meal diets of varying protein level to supply Lys from 80 to 120 of NRC (1984) from day-old to 18 wk of age. Performance with diets of 90% NRC Lys was equal to that with diets of higher Lys, provided that SAA were at 100% of NRC. Up to .2% Lys.HCl could be substituted into the 100 or 90% of NRC diets with no depression in performance, suggesting that the other essential amino acids were present in adequate amounts. When turkeys were fed diets of 85% of NRC (1984) Lys, maximum growth and breast meat yield were obtained with supplemental SAA at 100% during 0 to 18 wk of age and Lys at 100% during 12 to 18 wk of age. The requirements for other amino acids were supplied by diets formulated to provide 85% of the Lys requirement from protein. These values were for turkeys subjected to 18 C during final growout; they were not adequate in warmer temperatures.